CeMHOR's mission as a Center of Innovation (COIN) will be to optimize outcomes for Veterans by conducting innovative research to improve access to and engagement in evidence-based mental health and substance use care. CeMHOR's vision is that this COIN will be the premier Center in HSR&D and the nation for mental healthcare research, producing measurable improvements in access to and engagement in evidence-based mental healthcare by conducting cutting-edge, high-impact health services research, in close and continuous partnership with Veterans, clinicians, managers, and policy makers. VHA has implemented new policies and programs to increase the availability of evidence-based practices and to enhance access to care. Despite this health care transformation, there are gaps in scientific knowledge regarding how to improve access and engagement. Mental Health (MH) services research is desperately needed to inform efficient and effective allocation of resources as VHA strives to provide patient-centered, cost-effective, evidence-based MH services. CeMHOR's research goals and proposed projects were developed by working closely with Mental Health Services (MHS), Office of Mental Health Operations (OMHO), the VISN 16 Mental Health Product Line (MHPL), and several other partners: the Primary Care-Mental Health Integration Initiative (PC-MHI), the Office of Rural Health (ORH), and the Office of Informatics and Analytics (OIA). CeMHOR also has close relationships with research centers that promote dissemination and implementation including the South Central MIRECC, other MIRECCs, and Mental Health QUERI. As its high-impact, partnered-focused area of research, CeMHOR proposes research to advance knowledge and address gaps in access to and engagement in evidence-based MH care (Goal 1). Within Goal 1 are three objectives that aim to improve access and engagement for a) rural Veterans in primary care settings (as proposed in CeMHOR's approved CREATE); b) Veterans receiving care in specialty MH settings; and c) Veterans in the community who face challenges in accessing and engaging in mental healthcare. CeMHOR will also continue to support and advance innovative research outside the focused area (Goal 2). Because CeMHOR investigators have been major contributors to scientific advances in the rapidly developing field of implementation science, and have led the field in moving mental health services research along the implementation pipeline, the primary objective for this goal includes plans for ongoing contributions in this area. A secondary objective of this goal will be to support high impact research that, although it is outside CeMHOR's focus areas, will make significant contributions to improving care for Veterans. Goal 3 is to support mentoring and career development of MH services researchers. CeMHOR recruits talented investigators and fellows; provides formal mentoring and training programs, as well as a rich academic environment to develop their careers; and retains successful investigators. CeMHOR's advanced post-doctoral training program will emphasize methods to study and improve access and engagement; partnered research approaches; and implementation science methods, including hybrid effectiveness-implementation study designs. Goal 4 is to encourage and support clinical-research partnerships and cross-medical center research collaboration. CeMHOR will sustain existing and develop new partnerships with program offices, operations, frontline providers and Veterans, and promote collaboration with other VA investigators and Centers. At a time of dramatic change in VA mental healthcare, we propose a Center of Innovation (COIN) that will create new knowledge and have major impact on VHA mental healthcare and health policy.